Circuit interrupter



May 14, 1929. E. M. HEWLETT CIRCUIT INTERRUPTER Filed Aug. 16, 1925 lrwerfor` Edward M Hewle, b bf "f Patented May 14, 1929.

UNITED STATE-s PATENT OFFICE.

EDWARD M. HEWLETT, OIFl SCBYIENEG'IAIDY, NEW XOR/K, ASSIIIGNOIB.r TO GENERAL ELEC- TBIC COMPANY, A CORPORATION OF NEW YORK.

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Application led August 18, 1926. Serial No. 129,828.

This invention relates to circuitinterrupters, particularly those provided with magnetic blowouts for dissipating the arcs occurring Aupon the interruption of the circuit, and the principal object of the invention is to provide an improved magnetic arc blowout arrangement whereby the arc may be dissipated overa relatively long path within a limited space.

More specifically, the invention provides an improved magnetic arc blowout 'arranged to twist the'arc in a skew, orsubstantially spiral, inclosed path until the 'arc is extinguished. The preferred arrangement is l5 such that the arc is separated and different 'portions of the are 'are driven by .a magnetic blowout coil in op osite directions along inclosed skew, or spiral, paths to interrupt the circuit. In this way the are may be dissipated by expansion and extension to a very great length in an arc blowout inclosure having relatively small overall di mensions. Moreover, the pressure resulting from the passage of the' arcv along the inclosed paths materially assists in effecting the extinguishment of the are.

In a referred form of the invention, the circuit lnterrupter is provided with an inclosure or arc chute of arc-resisting material for receiving and dividing the arc from a switch of suitable form, and the arc chute inclosure has suitable barriers or dividing walls arranged to provide a plurality of skew, or substantiallyl spiral, inclosed paths for the arc about a co mon axis. This may be accomplished by sub-dividing the 'arc chute inclosure into three interconnected chambers, or compartments, located side by side with a suitable opening for receiving the arc in the middle chamber. A barrier of arc-resisting material in the middle chamber serves to divide the arc into two portions, and a blowout coil or winding is inclosed within the barrier and provided with suitable terminals on the opposite sides of the barrier for electrically connecting the separated portions of the arc through the winding or coil. The interconnections or openings between the adjacent chambers, :zi as well as the terminal plates of the blowout coil, are so designed and arranged that the blowout coil is energized by the current owing in the arc, and one portion of the arc is driven by the blowout coil from the m middle chamber into one Side chamber,

while the other ortion of thearc is driven into the other si e chamber. The increase in pressure due to the assage of the arc into each of the closed si e chambers compresses the arc stream and thereby aids in attenuating the arc. Thus, with theopenings between the middle chamber and the side chambers, as well as the barrier in the mlddle chamber, arranged to provide a substantially spiral inclosed path for the arcs, the blowout coil is so located that the magnetic flux drives each portion of the arc 1n' opposite directions along the spiral path.

I havek illustrated in the accompanying drawing a preferred form of circult interrupter having aymagnetic arc blowout embodying my present invention. Fig. 1 is a side elevation ofthe interrupter with the arc chuteshown partly in 'section in order to more clearly illustrate 'the various fea- 75 tures of constructionthereofg- Fig. 2 is a longitudinal' section of the arc blowout along the line 2 2; and Fig. 3 is a vertical e-c-ton of the arc blowout along the line The interrupter comprises essentially the kswitch V10 and the magnetic arc blowout chute 11 for receiving and dissipating the are from the switch 10. `As shown, the switch 10 is of the auxiliary break type havingthe main switch contact 12 arranged to be held in the closed position by the latch 13, and the auxiliary or arcing switch member 14 held in engagement with the arcing contact 15 by `means of the compression spring 16. The arcing contact 15 extends into the arc chute 11, as indicated in the., drawing, and the auxiliary arcing switch member 14 is rotatably mounted to Swingin close' proximity to the opposing arcingcontact or terminal 17, which also is located within the magnetic arc blowout inclosure 11.

'I he blowout coil 18 is inclosed within the arc barriers 19 and preferably is disposed directly above the arcing terminals 15 and 100 17. 'f A's more clearl shownin Figs. 2 and 3, the magnetic are c ute 11 is a box-like inclosure, formed of suitable arc-resisting material, such as asbestos board or the like, and is. subdivided into the arcing chambers 105 -indicated as A, B and C. The blowout coil 18 and the arcin terminals 15 and 17 are located in the mi dle arcing chamber, which connected with the adjacent arcingchambers by means of the restricted openings or vwindows and 21. The purpose of the subdivided arcing chambers and the interconnecting windows in the arc chute is to provide a skew, or substantially spiral', inf closed path of increasing area the combined action ofthe increasing pressure and thev magnetic flux of the blowout winding or coil 18, as will be more fully set forth hereinafter. The blowout coil 18 has one terminal connected to the metallic terminal plate or'strip 22, which is secured uponone side 'of the'barrier 19 with one end extending down into proximity to the arcing terminal 15 and the other end carried up and through the opening, or window, 20.

into the arcing chamber B. The other 'terminal of the blowout coil 18 also is connected to a terminal plate or strip 2 3, which is secured to the other side ofthe barrier 19 with one end near the arcing contact 17 and the other end extending from the middle chamber A into the adjacent arcing chamb'er C. y

For the purpose of initially driving the arc formed upon separation of the relatively movable switch members 14 and 15 into the magnetic blowout chamber, an auxiliary arc blowout coil 24, having the magnetic Huxdistributing members 25 dis osed on oppo. site sides of the switch mem er 14, may be provided if desired. The auxiliary blowout coil 24 is lconnected between the main circuit conductor L1 and the arcing terminal 15,

while the' other arcing terminal 17 lis con-- nected directly to the main circuit conductor L2, as indicated in Fig. 1..

My improved circuit interrupter operates in the following manner: When the latch' is. released, the main switch member 12 is operated to the 'open position by thebiasing spring 26, and after a short initial movement engages with-the auxiliary or arcing .switch member 14 to o erate the latter out of engagement with t e arcing terminal. 15. vUpon the initialcpening of the main switch -member 12, all of thecurrent flowing inthe main circuit conductors L1, L, passes through the auxiliary switch member 14, the arcing contact 15, and the blowout coil 24.V Thus,

the auxiliary magnetic blowout 24 is energized to set-up a flux for blowingthe arc contact with vthe terminal drawn upon the disengagement ofthe movable switch member 14 along which thel arc may be ,driven and attenuatedby" 'within the chamber B to the cham rom the arcin' -terminal 15 into the main magnetic arc c ute -11.

the blowout coil 18 reacts to drive the righthand portion Aof the arc in a counter-clock wise ldirection and the left-hand portion of the arc in a clockwise direction.- The righthand arc quickly travels along the arcing tei'minal 15 until one end of the arc reaches the' terminal knob 26 and the other end of the arc reaches the upper end of the plate 22.' All the whilethe arc is being extended and expanded, as indicated by they dotted lines in Fig. ,1, until the arc finally passes through the opening, or window, 20 into the adjacent chamber B. Thereu on, the magnetic flux of the blowout coil 8 serves to further expand and drive the are in a substantially spiral path, as indicated by the gradually expanding dotted lines. The Y heating effect of the arc upon the air within the inclosed chamber B, causes the pressure rapidly increase.

In this wayl .a pressure is built up which i m vterially aids in extinguishin it s elongated in the spiral patlgi within the er B. At the same time, the lefthand arc between the arcing terminal 17 and the strip 23 is driven bythe linx of blowlout co il 18 ina clockwise direction. This results 1n one end of the arc traveling along the arcingterminal l17 until it reaches the terminal knob 27, while the other end of the arc travels to the upper end of. the strip 23. Furtherfreaction off-the blowout coil expands the are through thevvindow 21 intothe arcing chamber C, where it is ex? panded andv driven in a counter-clockwise direction about the axis of the coil in substantially the same manner as the right-hand arc 1s interruptingthe circuit, the operation o the. magnetlc blowout just described occurs substantially instantaneously or atleast in a very short space of time, and the separate portions of the arc are ,thus

uickly twisted in opposite directions until t e arc breaksand the circuit between the line conductors L1, L2 is interrupted.

While I have described the preferred embodiment of my invention, it will be evident to those skilled in the art that various changes and modifications can be made `in the apparatus shown, without departing'l from'the spirit of the invention. v

What I claim as new, and desire to secure by'Letters Patent of the United States, is;

1. Acircuit interrupter comprising rela-- tively movable switch members, an inclosure of insulating material having an opening disposed to receive the arc roduced upon relative movement between said switch 'members and having barriers arranged to provide a lurality of y interconnected chambers wit in the inclosure formin a substantially spiral inclosed path for bu ding'up a pressure upon assage of the arc therethrough, and a win ing ocated in an intermediate the arc as ,expanded in the arching chamber B. In. actuall f `sure disposed to receive the arc from said switch members having a plurality of interconnected' arcing chambers providing a substantially spiralY inclosed path lforI building up a pressure within said chambers upon passage of the arc through said path and a winding located in an intermediate one of saidI arcing chambers and connected to be energized in accordance with the current in the arc for setting up a magnetic flux substantially along the axis of the spiral path in the direction required to drive the arc around said path.

3. A circuit interrupter comprising relativelyT movable switch members, an inclosure of insulating material providingthree interconnected 'arcing' chambers disposed in substantially parallel relation and having a restrictedopening in the middle one of said chambers for receiving the arc from said switch members, a barrier located in said middle chamber for separating the arc received through said opening, the interconnection between said chambers providing a substantially spiral inclosed path for each portion of the arc about a common axis, and a winding inclosed within said barrier and my hand this having terminal connections for completing the circuit between the separate portions of the arc, said winding being arranged to set up a magnetic flux substantially along the common axis of said special paths to drive the said portions of the arc in opposite directions therealong.

4. A circuit interrupter comprising relatively movable switch members, an inclosed arc chute divided into aplurality of substantially parallel interconnected arcing chambers and having an opening for receiving the arc from said members .into an intermediate one of the chambers, a barrier in said intermediate chamber for separating,

the arc received through said opening, the interconnections between said chambers providing a twisting path for each portion of the arc extending from the intermediate chamber to the adjacent chamber on an opposite side thereof, a winding inclosed with- 1n said barrier, and terminals for the winding'secured to opposite sides of the barrier,

and each extending into the chamber on an opposite side of the intermediate chamber, whereby the winding ,is interconnected between the separate portions of the arc to set up a magnetic field to drive the portions of the arc along said terminals into the adjacent arcing chambers.

In witness whereof, I have hereunto set 13th day of August, 1926. EDWARD M. HEWLETT. 

